It is not always easy to write about a favourite book or even to understand why some works are so much more meaningful to us than others. But with Jennie Gerhardt, Theodore Dreiser's second and intensely tragic novel, I am acutely aware of how much of the book's power is, for me, tied to memories of the last days in the life of my mother, Caroline Benn, proud American, socialist, scholar, lover of 19th-century novels and a great admirer of Dreiser.

In the autumn of 2000, when she was dying of cancer, slowly and painfully but with tremendous humour and bravery too, my mother and I talked with the intensity of those who know time is fast running out. It may even have been her who urged me to read Jennie Gerhardt. I had seen her taking notes on the novel, part of her research for her sadly unfinished final project, to write a history of socialists and the socialist movement in America. Jennie Gerhardt is largely set in Ohio, her dearly loved home state to which she returned for a long visit every year.

Analytical to the last, my mother saw Dreiser's novel largely as a forensic dissection of a particular moment in American capitalism while I admitted to bouts of uncontained weeping at the cruelty of the story's conclusion, the human tragedy of Jennie herself.

It's obvious to me now, and as it was to her then, that my profound sadness was intimately connected to her terminal illness and - a slightly different thing, this - our shared knowledge of her imminent death. Dreiser writes powerfully of the simple tragedy of mortality itself - rich or poor, his characters expire acutely aware of their existential isolation - but he also touches directly on the poignant truth that, however vulnerable a mother may be, she is always, if a good mother, in some way more protective of her child than of herself.

In one of the saddest parts of the book Jennie Gerhardt is forced to hide the fact of her illegitimate daughter Vesta's existence from her rich lover, a decision she comes bitterly to regret and so revoke, only later on to lose Vesta to a childhood illness just at the moment she needs her most. As the mother of two very young girls, facing the impending death of my own mother, this was just all too painful to contemplate, even in fiction.

But sorry, let me do my job, and tell you the story, should you be interested in picking up this book.

Set in Ohio in 1880, Jennie Gerhardt tells the story of a lovely innocent young woman, the eldest daughter of a narrow-minded but proud, disabled and therefore unemployed German immigrant, who is forced to seek work to keep the family in food and warmth.

In the course of the novel she finds love not once, but twice, both times with powerful older men; first, a lonely but tender-hearted Senator, whom she meets when she works as a cleaner in a large hotel, but who dies suddenly leaving Jennie pregnant and a social outlaw.

Later on, she becomes the lover of the impatient but magnetic Lester Kane, scion of a railway-owning family, who sets up house with her, but is eventually forced, through financial and moral pressure, to abandon Jennie and marry a much more suitable and cultured woman, even though he loves Jennie to his dying moments.

The rise and fall of a beautiful but ultimately powerless woman is a common narrative arc in much great American fiction from Henry James's Daisy Miller to Edith Wharton's The House of Mirth. Jennie is a personality of rare goodness and innocence, who stoically accepts her unjust fate. She feels no bitterness, even when, by the end, she is abandoned, through death or desertion, by everyone she truly loves.

Dreiser's genius lies not just in his raw narrative urgency, but in his ability to show how love and money are always entwined, how our fate is determined less by character than by the deepest-rooted structures and often unspoken rules of society.

Jennie may possibly be a little too good to be true but even those characters who are found wanting are so fully drawn, so wonderfully alive, in both good and bad aspects, that we completely understand why they do what they do.

As Dreiser shows us, without irony, rich men have to keep making money to keep being rich; they must surely have suitably charming and attractive wives. And even clever, independently wealthy women, like Letty Pace, the woman Lester Kane eventually marries, have to lure a suitable mate, with all due sympathy, intellect and charm, in order to sustain their worldly position - even if, as in this case, it leads directly to the effective 'elimination' of another woman with less social power.

Dreiser, who went from rags to riches himself, not once, but twice in his lifetime, has the rare gift of writing convincingly about both wealth and poverty. He can convey the urgency of the poor man's search for work, the child scrabbling for coal, a care-worn mother's helpless anxiety.

But he writes equally evocatively about the exciting sparkle and deep velvety comfort of wealth, its allure and power, and ultimately its emptiness. Jennie's ambitious elder brother, Bass, longs to move with a smart crowd.

Clothes were the main touchstone. If men wore nice clothes and had rings and pins, whatever they did seemed appropriate. He wanted to be like them and to act like them, and so his experience of the more pointless forms of life rapidly broadened.

Re-reading Jennie Gerhardt this last week, I got as much pleasure from phrases such as these, with their searchlight power to reveal hidden recesses of human motivation - surely one of the great moral pleasures of fiction - as I did from the powerful story line and its tragic ending.

Yes, I was still touched and deeply upset by the fate of this kind, unlucky, always loving and almost unbelievably stoical young woman from Ohio. But this time I found myself doing something else: feverishly marking, on a bus journey or curled up in a chair at two in the morning, particularly prescient observations. 'Clothes were the main touchstone...' 'The more pointless forms of life'. I was saying to myself, constantly: Ah yes! And so in Dreiser's company I continue to feel just that little bit less alone in the world: one mark of a great writer.

[All the pieces that have appeared to date in this series, with the links to them, are listed here, here, here and here.]